This invention relates to a connection between a spinal rod and a vertebral anchor with a tapered locking surface that traps the vertebral anchor in the connection fitting.
Spinal implant systems provide a rod for supporting the spine and for properly positioning components of the spine for various treatment purposes. Bolts, screws, and hooks are typically secured to the vertebrae for connection to the supporting rod. These vertebral anchors must frequently be positioned at various angles due the anatomical structure of the patient, the physiological problem being treated, and the preference of the physician. It is difficult to provide secure connections between the spinal support rod and these vertebral anchors at all the various angles and elevations that are required, especially where there are different distances between the rod and bolts and where these components are located at different heights on the patient.
What is needed is a connection assembly between a spinal rod and a vertebral anchor that allows the surgeon to fix the desired elevation between a rod and the bone anchor as well as fix the desired angle between the anchor and rod. The following invention is one solution to that need.
In one aspect, this invention is a connection assembly between a spinal implant rod and a vertebral anchor. The connection assembly includes a longitudinal member with a friction shoe at one end and an aperture at the other. The connection assembly also includes a housing. The housing has a passageway to receive a portion of the vertebral anchor and a bore to receive at least a portion of the shoe of the longitudinal member. The housing also includes a rod interface washer. The washer is positioned over the longitudinal member between the aperture of the longitudinal member and the face of the housing. The connection assembly further includes a compression member. The compression member is forceably, for example threadably, engageable into the aperture of the longitudinal member to urge the rod toward the vertebral anchor, whereby the shoe will be moved in the bore to urge the vertebral anchor toward the internal wall of the passageway in the housing, further pressing the housing and said rod interface washer together.
As used in this specification the term xe2x80x9cshoexe2x80x9d means a structure that retards, stops, or controls the motion of another structure. WEBSTER""S NINTH NEW COLLEGIATE DICTIONARY 1088 (1990).